Numerous discharge (i.e.: flush) valve systems currently exist. All of these systems use various actuators that mechanically cause the flush valve to open and close. Some of these designs selectively permit either partial flushing or full flushing. Although many of these designs are generally acceptable, they often require considerable energy to operate their actuators.
What is instead desired is a discharge flush valve system that requires only minimal energy to operate. The present invention provides such a system. This is because the present system uses the buoyancy of the water itself in the toilet tank to control the operation of the discharge valve flushing.